AppleCorey

Hey, I'm new to adding mods to servers and have no Idea what I'm doing I've got my server and am trying to use galaticraft, but the mod which has Tin, Copper etc is working so I can't really do much, but use the ores found in vanilla. Can someone please give me a really dumb'd down version on how to get around this and get mods working on my server for me and my friends. Thank you.